package fileDown;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.IOUtils;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.List;

public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.获取要下载的文件名
        String downloadFileName="2.jpg";
        //2.读取要下载的文件内容，通过ServletContext对象可以读取
        ServletContext servletContext=getServletContext();
        InputStream resourceAsStream=servletContext.getResourceAsStream("/file/"+downloadFileName);
        //获取要下载的文件类型
        String mimeType=servletContext.getMimeType("/file/"+downloadFileName);
        System.out.println("下载的文件类型是："+mimeType);
        //3.在回传前通过响应头告诉客户端返回的数据类型
        resp.setContentType(mimeType);
        //4.通过响应头告诉客户端收到的数据是用于下载使用,且设置客户端要下载的文件的命名
        resp.setHeader("Content-Disposition","attachment;filename="+ URLEncoder.encode(downloadFileName,"UTF-8"));
        //获取响应的输出流
        OutputStream outputStream= resp.getOutputStream();
        //5.把下载的文件内容回传给客户端
        //读取输入流中的全部数据，复制给输出流，输出给客户端
        IOUtils.copy(resourceAsStream, outputStream);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1 先判断上传的数据是否多段数据（只有是多段的数据，才是文件上传的）
        if (ServletFileUpload.isMultipartContent(req)) {
//           创建FileItemFactory工厂实现类
            FileItemFactory fileItemFactory = new DiskFileItemFactory();
            // 创建用于解析上传数据的工具类ServletFileUpload类
            ServletFileUpload servletFileUpload = new ServletFileUpload(fileItemFactory);
            try {
                // 解析上传的数据，得到每一个表单项FileItem
                List<FileItem> list = servletFileUpload.parseRequest(req);
                // 循环判断，每一个表单项，是普通类型，还是上传的文件
                for (FileItem fileItem : list) {

                    if (fileItem.isFormField()) {
                        // 普通表单项

                        System.out.println("表单项的name属性值：" + fileItem.getFieldName());
                        // 参数UTF-8.解决乱码问题
                        System.out.println("表单项的value属性值：" + fileItem.getString("UTF-8"));

                    } else {
                        // 上传的文件
                        System.out.println("表单项的name属性值：" + fileItem.getFieldName());
                        System.out.println("上传的文件名：" + fileItem.getName());

                        fileItem.write(new File("e:\\" + fileItem.getName()));
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}
